1. Field of the Invention
The present invention relates to a composite particle with a shell layer that is a carbodiimide resin layer, and a process for producing the same, more particularly a composite particle with a shell layer that is a carbodiimide resin layer comprising a base particle (A) having a functional group and a carbodiimide resin (B), characterized that the shell layer comprising a carbodiimide resin is formed to cover surface of the base particle (A) by bonding between functional groups of the base particle (A) and carbodiimide groups of the carbodiimide resin (B), and a process for producing the same.
2. Description of the Prior Art
A carbodiimide compound (or a carbodiimide resin), having structure of —N═C═N—, has been widely used as a stabilizer for improving hydrolysis resistance for compounds having an ester group or crosslinking agent for resins, e.g., (meth)acrylic resins, having a carboxyl group reactive with a carbodiimide group, where high reactivity of a carbodiimide group is generally utilized.
Various applicable areas have been proposed for carbodiimide resins, e.g., paints, adhesives and coating agents, as disclosed by Japanese Patent Application Laid-Open Nos.10-60272 and 10-30024, and they have been already commercialized in these areas.
However, most of the resins to be crosslinked with a carbodiimide-containing composition are in the form of a molten resin solution, paste or emulsion. Hardening of solid particles themselves requires a great deal of time and is hence difficult.
Production of polyolefin-based resin particles of crosslinked structure by the reaction with a carbodiimide compound in a melting/kneading machine or the like has been studied, as disclosed by, e.g., Japanese Patent Application Laid-Open No.2000-155441. However, the particles which can sufficiently satisfy resistance to heat and chemicals and sufficiently utilized own reaction performance of a carbodiimide resin have not been developed.
Broadly speaking, the processes for producing polymer particles fall into two general categories; (I) production of the objective particles by crushing and classifying the resin produced by, e.g., mass or solution polymerization, as known, and (II) production of adequate (spherical) particles during a polymerization stage, e.g., suspension, emulsion, dispersion or dropping polymerization, or seed processes based on these processes.
When hardened particles are to be produced, most of these approaches incorporate a crosslinkable vinyl-based monomer or polymer to improve resistance to heat and chemicals, or incorporate a crosslinkable monomer or polymer other than a vinyl-based one, e.g., an epoxy resin or the like, to improve resistance to heat and solvents.
In these cases, various particles have been practically used as satisfying resistance to heat and chemicals such as in spacers for liquid crystals, reinforcing materials, modifiers, and the like, however, there have been no particles by applying a carbodiimide resin and satisfy resistance to heat and chemicals.
Further, there are such particles found as having a reactive group such as a carboxyl group, a hydroxyl group, an amino group, and the like by applying a seed polymerization process, and the like, however, they are not sufficient to easily react with such resins with high level of reactive groups such as a carboxyl group, a hydroxyl group, an amino group, and the like as in a (meth)acrylic resin and thus there have been no practical attainment of particles providing sufficient utilization of reactive performance and with good mechanical and functional characteristics.